A transformer is a device which uses the principle of the electromagnetic induction to change an alternating voltage. For instance, an existing transformer mainly comprises a primary coil, a secondary coil, and a magnetic core. In the case that an alternating current (AC) appears in the primary coil, an AC flux is generated in the magnetic core so as to induce a voltage (or a current) in the secondary coil.
The main functions of the transformer comprise voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization, etc.